Editing preferences

I downloaded the Arduino IDE software, installed it, and got off to a great start. I built several simple Sketches, edited and ran them with no problem. Then I decided to customize the IDE appearance because some of the font colors were so pale that it was hard to read them in bright ambient light. I found the instructions at http://www.instructables.com/id/Change-Arduino-Font-Color/ and tried it. At first I could not edit preferences.txt, so I changed the permissions and added the lines shown in the instructions. After that, I could not edit an .ino file at all. I deleted my changes to the preferences.txt file, and still I could not edit. Finally, I uninstalled Arduino, made sure all the program files were deleted and reinstalled. Still I cannot edit an .ino file.

The IDE editor shows the entire text of the file with a gray background, and the text is unresponsive to any delete, backspace or insert test commands.

Help!

DrWiggly:
The IDE editor shows the entire text of the file with a gray background, and the text is unresponsive to any delete, backspace or insert test commands.

To fix this try File > Preferences > Use external editor(uncheck)